A former secretary of Oxford author CS Lewis is giving away signed first editions of the author’s Narnia books to raise money to renovate a city church.

The Oxford Oratory Church of St Aloysius, in Woodstock Road, is set to receive the windfall thanks to the generosity of Walter Hooper.

The church is launching a £3m appeal to carry out renovation work and build a new chapel and student accommodation.

Mr Hooper, 77, who lives in North Oxford, briefly worked as CS Lewis’s private secretary in 1963, shortly before the author’s death.

After Lewis’s death, Mr Hooper devoted himself to The Lion, The Witch and The Wardrobe author’s memory and co-wrote the author’s biography, and edited his letters and diaries.

He said: “I have kept these books close to me all these years but when this appeal came up, I wanted to do something.

“In a way it will be a wrench to part with the books but in another way I’m glad, because they might do some good.

“CS Lewis gave away two thirds of his income and it was wonderfully liberating to see a man who did not seem to amass wealth at all – he really was a good man.”

Mr Hooper will retain a copy of Lewis’s poetry volume Spirits in Bondage, because he still finds inspiration from the verses.

Mr Hooper has donated 11 CS Lewis titles, including three signed first editions – The Voyage Of The Dawn Treader, The Horse And His Boy and The Last Battle.

All 11 books are estimated to sell for up to £3,000 each at auction in London next month, with the hammer price boosted by the release today of the movie version of Prince Caspian. The books will be auctioned by Sotheby’s in London on July 17.

This year marks the 110th anniversary of Lewis’s birth in Belfast on November 29, 1898.

Philip Berrington, books specialist for Sotheby’s, said: “With the film of Prince Caspian coming out, the timing for this auction couldn’t be better. The connection between Walter Hooper and CS Lewis makes these books very collectable.”

The Oxford Oratory was built in 1875. Redecoration will restore marble, stonework and stencilling of the original Victorian design.

A smaller chapel for Masses, pilgrimage groups and baptisms will be added, together with a small garden.